BMI Calculator

Use this free adult BMI calculator to estimate your body mass index from your height and weight. BMI is a screening measure and does not diagnose an individual's health or body composition.

How BMI Is Calculated

For measurements in pounds and inches, BMI is calculated by dividing weight in pounds by height in inches squared and multiplying the result by 703.

BMI Formula

BMI = 703 × weight (lb) ÷ height (in)2

Adult BMI Categories

For adults, commonly used BMI categories are: underweight below 18.5, healthy weight 18.5 to 24.9, overweight 25.0 to 29.9, and obesity 30.0 or higher.

Example

A person who weighs 180 pounds and is 5 feet 10 inches tall has a BMI of approximately 25.8.

Important Limitations

BMI is a screening measure rather than a direct measurement of body fat. It does not distinguish fat from muscle or account for all differences in age, sex, body composition, pregnancy, or individual health circumstances. Discuss questions about weight or health with an appropriate healthcare professional.

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Understanding Body Mass Index (BMI)

Body Mass Index (BMI) is a screening measurement that compares a person's weight with their height. It can help identify weight categories associated with certain health risks, but it does not directly measure body fat or diagnose a medical condition.

How Is BMI Calculated?

BMI = Weight in kilograms / (Height in meters × Height in meters).

For example, an adult weighing 80 kg with a height of 1.75 meters has a BMI of approximately 26.1.

Adult BMI Categories

These categories generally apply to adults aged 20 years and older. Children and teenagers require age- and sex-specific BMI percentiles.

Limitations of BMI

BMI cannot distinguish muscle from body fat. Athletes, older adults, pregnant individuals, and people with different body compositions may require additional clinical assessment.

Frequently Asked Questions

Is BMI an accurate measure of body fat?

Not always. BMI is a screening tool rather than a direct measurement of body fat.

Can someone have a normal BMI and still have health risks?

Yes. Blood pressure, cholesterol, blood glucose, waist circumference, and other factors also influence overall health risk.

Should BMI be used to diagnose obesity?

BMI can help identify possible obesity, but clinical assessment should consider additional measurements and individual circumstances.

Educational information only. This calculator does not replace professional medical advice.